The invention relates to a method for producing a core card for a laminate, to a core card with a laminar system, to the use of such a core card for producing a laminate, to a laminate with such a core card as well as to an apparatus for producing such a core card.
Laminated laminates are usually composed of multiple plies of core card layers impregnated with resin, which are merged under high pressure. As web-shaped support materials, such laminates constitute the basis for worktops, window sills, linings, room claddings, partitions and many more. The core card layers are produced from individual plies of identical or different core cards, which can basically also be referred to as core papers or core paperboards according to grammage. Each core card in turn has a laminar system with one or more layers of fibrous materials. Depending on the respective purpose of employment of the laminated laminate, further layers or plies of other materials for satisfying certain characteristics can also be provided besides the layers or core cards. Furthermore, non-laminated laminates are also known, in which multiple layers or plies of core cards are pressed to each other without the aid of resins.
For a long time, core cards and papers were exclusively produced of fresh fiber materials to be able to satisfy the specific requirements to core cards with regard to tear strength, capability of impregnating, capability of further processing, optical impression and the like. In order to reduce the consumption of natural resources and the raw material cost associated with the use of fresh fiber material, in the meantime, some core cards are at least proportionally produced of recycled waste paper. Such a core card as well as a corresponding production method of such a core card can for example be taken from WO 2011/141355 A1. The core card described there is at least proportionally composed of a reprocessed fibrous mixture and includes in particular surface-active ingredients for increasing the capillarity of the core card as additives besides wet strength agents. The capillarity presents an important influencing variable for the capability of impregnating core cards with resins.
It has proven disadvantageous in the presently known core cards, which are at least proportionally produced of waste paper, that they have a comparatively high abrasiveness with respect to separating tools such as for example cutting, sawing and the like. This disadvantageously affects the idle times of the tools used for producing laminates since the corresponding grinding and cutting tools hereby have a shortened lifetime and have to be more often exchanged. A further disadvantage is in the use of surface-active ingredients, which present a load of the water circulation system on the paper machine, which can disturb the chemical equilibriums of the machine cycle of card machines, result in increase of the production cost and not least cause environmental and waste water loads.